The glycolytic pathway is quantitatively the chief metabolic route of most cells, normal and diseased. Although differing in details between higher and lower cells, it is the same pathway and the same biochemistry in microbes and presents, in them as in higher cells, avariety of matters still being clarified. These include questions of isoenzyme function, allosteric controls, glucose uptake, the possibility of an enzyme complex, and the issue of how flux is determined in vivo, as well as description of its genetics. Our work, with Saccharomyces cerevisiae and Escherichia coli, touches on most of these points. The current focus is on the hexokinases and their roles in glucose uptake (in yeast), the fructose-6- P/fructose-1,6-P2 interconversion (in both organisms), and the aldolases (in E. coli), and several projects, including the latter, concern phosphorylation of enzymes and its mutational alteration. We also propose work on the putative glycolytic complex, and some new lines relating to the description of metabolism as a whole, which derive from having a variety of strains with high level or altered enzymes. These include experiments on rate limitation in the pathway and on transit time.